This invention relates to combine harvesters and has particular reference to such machines having a threshing and/or separating mechanism comprising a rotor and concave means which extend at least partially around the rotor at a location above the axis of rotation of the latter.
In combine harveters of the type indicated a problem can arise with regard to the adequate removal of grain separated through the concave at locations above the axis of rotation of the rotor inasmuch as there is a tendency for separated grain to build up on the concave and thus impair the further operation thereof. This is particularly so in machines having a concave which extends essentially totally around the rotor, the problem of excessive grain build up being paramount at the upper portion of such a concave.
In U.S. Pat. No. 4,108,150 there is disclosed a combine harvester of the axial flow type in which a threshing rotor is surrounded by a concave and a plurality of fingers are disposed close to the concave on the side remote from the rotor and spaced axially of the rotor. The fingers are mechanically vibrated so as to agitate grain and any other crop material passing through the concave so that air flowing through the concave as a result of rotor rotation can dislodge this material to make it fall to a mechanism for distributing that material to other components of the machine. It is found, however, that mere agitation of the grain, etc. is insufficient to ensure the necessary movement thereof from the concave, particularly from the upper portion of the latter.